Porphyria cutanea tarda (PCT) is often severe and difficult to treat when associated with end stage renal disease. Erythropoietin deficiency causes anemia and prevents treatment of these patients by phlebotomy. Erythropoietin administration, which can mobilize excess iron, correct anemia and support phlebotomy, is being studied in 20 patients with this condition. Aims are to closely monitor the effects of erythropoietin treatment on plasma porphyrins and measures of iron status, and develop clear guidelines for treatment.